A two-part study is being undertaken to evaluate a hepatitis B vaccine being produced by NIAID. In the first phase, baseline seroepidemiologic data will be obtained in 10 dialysis units in NYC and the Metropolitan Washington Renal Dialysis Unit. When the hepatitis B vaccine is available (approximately Fall of 1977) a prospective, controlled, randomized double blind trial of its efficacy will be undertaken in these same dialysis units.